Evidence of specialized leukocyte-vascular homing interactions at the maternal / fetal interface

Abstract

In normal pregnancy, the maternal immune system fails to reject the fetus or the placenta as an allogeneic graft. We hypothesize that specialized mechanisms of leukocyte recruitment might limit access of circulating maternal immune cells to the maternal/fetal interface. During the critical period of initial trophoblast invasion there is an elegantly orchestrated progression of leukocyte homing events in the decidua basalis, associated with highly regulated expression of vascular addressins and segregation of specialized leukocyte subsets into well-defined decidual microdomains. Neutrophils are limited to the region of necrosis associated with enzymatic digestion at the leading edge of the invading trophoblast, where an almost linear array of maternal blood vessels displays the neutrophil ligand E-selectin. Cells with the phenotype of monocytes but expressing § 4 g 7 integrin are localized in the blood vessels of the specialized "vascular zone", which display the unusual combination of P-selectin (partially associated with platelets) and the § 4 g 7 ligand mucosal vascular addressin-1 (MAdCAM-1). Granulated metrial gland cells (§ 4 + g 7-, probably § 4 g 1 +) constitute a well-defined cluster positioned in the central decidua basalis around venules prominently expressing the § 4 g 1 ligand VCAM-1 (but not MAdCAM-1). T and B lymphocytes are rare. Our results suggest that selective mechanisms for regulating leukocyte access, associated with microdomain specialization within the decidua basalis, may play a fundamental role in immune regulation during the invasive period of placental development.

Semen activates the female immune response during early pregnancy in mice

“…However, there was a similar propensity for PALN cells to home to other mucosal tissues particularly the small intestine and the lung. This is consistent with expression in uterine venule endothelial cells of mucosal addressin cell adhesion molecule‐1 38 the ligand for integrin α 4 /β 7 responsible for common lymphocyte homing properties across mucosal tissues.…”

ORIGINAL ARTICLE: CD56+ Cells are Recruited to the Uterus in Two Waves: at Ovulation and During the First 2 Weeks after Missed Menses

“…This combination of homing molecules and chemokine receptors enables CD56 bright cells to move into secondary lymphoid tissue. The highly specialized and specific localization of CD56 bright cells and their close associations with dendritic cells and macrophages suggest that the decidualizing uterus is a transitory secondary lymphoid tissue 19 …”

Neither lymphotoxin α nor lymphotoxin β receptor expression is required for biogenesis of lymphoid aggregates or differentiation of natural killer cells in the pregnant mouse uterus

“…Interestingly, Kruse et al . have reported studies conducted prior to full differentiation of the MLAp (gd 8·5 by our counting), showing that endothelium in DB has unique expression of V‐CAM‐1 in the absence of MAd‐CAM 25 . We have shown recently, in transplantation studies using pregnant alymphoid recipient mice, that uterus does not contain self‐renewing uNK cell precursors 26 .…”